In western Pennsylvania, we call it an onion snow: the last snow of the season, late enough that you can see the tops of the onions through the snow. It’s the cue for every good Pittsburgher to say, “We’ve never had weather like this before.”

Winter is a beautiful time of year, but sometimes in the cold and snow it’s good to remember summer. Here’s a small taste of midsummer in the woods and meadows around Pittsburgh.

The rough-fruited cinquefoil, Potentilla recta.

A woodland waterfall.

A red clover, Trifolium pratense.

A white clover, Trifolium repens, in an unusually strong bicolor.

A birdfoot trefoil, Lotus corniculatus.

When you come across any wildflower in Pittsburgh and nearby, Wildflowers of Western Pennsylvania is an essential resource. Dr. Bob Zuberbuhler has built a unique and comprehensive Web reference, both informative and beautiful.

One of the small delights of city life is the weeds. In the country, we take weeds for granted. But in the city, weeds are often garden escapes that flourish in unlikely places. Here are three urban weeds from half a block of the same street:

A morning glory growing from a crack in the sidewalk. This is actually a native wildflower, but often grown in gardens around here.

A patch of alyssum growing along the edge of the sidewalk.

Red snapdragons dangling from a low retaining wall.

Rosa multiflora (it has no common name except “multiflora rose” and some nicknames too impolite to repeat here) is a noxious and invasive weed that can take over whole hillsides with its thick, rambling, thorny shoots. In June, it’s also one of our most beautiful flowers, covering itself with clusters of white roses and filling the air with rose perfume.

Here are two versions of a Rosa multiflora picture that will make a splendid desktop wallpaper for your computer. Nothing is more restful, or more conducive to productive work, than a view of green leaves and white flowers. Click to enlarge; right-click to download the full-size version.

The wide-screen version is for typical wide-screen screen resolutions of 1680 by 1050 or smaller.

The standard version is for screen resolutions of 1280 by 1024 or smaller.

Stream valleys with precipitous slopes—too precipitous even for Pittsburghers to build on—cut through the city and suburbs everywhere. In the spring, wild woodland flowers take advantage of the last few days before the leaves come out and the shade closes in. These flowers all grew within a few yards of each other in the Squaw Run valley.

Trillium grandiflorum, Large-Flowered Trillium

Mertensia virginica, Virginia Bluebells

Claytonia virginica, Spring Beauty

Phlox divaricata, Blue Phlox

Trillium erectum, Wake-Robin (white form)
[In an earlier version of this article, this was misidentified as Trillium cernuum.]

Tiarellia cordifolia, Foamflower

Viola pallens, Northern White Violet

Viola pennsylvanica, Smooth Yellow Violet